The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
Meal Supplements For Weight Loss — What Works in the UK
Meal replacement supplements can be a helpful tool for reducing calorie intake, but evidence shows they work best as part of a structured weight management approach. If you're looking to lose weight in the UK, you have several options — from dietary changes to NHS weight loss programmes and prescription weight management medications. This guide explains what's available, who's eligible, and how to find the right approach for your health needs.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
UK-Licensed Prescription Weight Loss Options
For adults struggling with weight management, the UK has three prescription-only medications licensed specifically for weight loss. These work alongside diet and physical activity, not instead of them.
- Mounjaro (tirzepatide) — A once-weekly injection that activates two hormone pathways (GIP and GLP-1). Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks, though individual results vary.
- Wegovy (semaglutide) — A once-weekly GLP-1 injection. In clinical trials, participants lost approximately 15% of body weight on average.
- Saxenda (liraglutide) — A daily GLP-1 injection offering similar benefits but requiring daily administration.
All three are prescription-only and require a clinical assessment before prescription. They're most effective when combined with reduced-calorie diet and increased physical activity, similar to how meal supplements work best within a broader weight management plan.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
NHS vs Private Access — How to Get Started
In the UK, prescription weight loss medication is available through two routes: NHS specialist weight management services or private prescribing following an online consultation.
NHS route: Your GP can refer you to a tier 3 specialist weight management service if you have a BMI of 30 or above (or 27 if you have weight-related health conditions like type 2 diabetes or high blood pressure). NHS access is free but often involves waiting lists.
Private route: Available through registered online prescribers and dispensed by GPhC-registered pharmacies. This typically has shorter wait times but involves private costs.
Your GP is the best starting point. They can discuss whether prescription medication is suitable for you based on your individual health, check your BMI using a standard assessment, and refer you to appropriate services.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Are meal replacement supplements enough for weight loss?
Meal replacements can help reduce calorie intake and may support modest weight loss, but evidence shows they work best as part of a structured approach including physical activity and behaviour change. For significant or sustained weight loss, prescription medication under medical supervision is often more effective.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are once-weekly injections, but Mounjaro is a dual GIP/GLP-1 agonist while Wegovy is a GLP-1-only agonist. Clinical trials suggest Mounjaro may produce slightly greater average weight loss (15–21% vs 15%), though individual results vary considerably. Your prescriber will advise which is more suitable.
Who can get weight loss medication on the NHS in the UK?
Adults with a BMI of 30 or above, or BMI of 27–29.9 with weight-related health conditions (diabetes, high blood pressure, heart disease), may be eligible. Referral comes through your GP to a specialist weight management service. Eligibility varies slightly by region and ICB.
Can I use my BMI to check if I'm eligible for weight loss treatment?
Yes — you can use our free BMI calculator to check your personal BMI instantly. If your BMI is 27 or above (or 30+ without comorbidities), you may be eligible. Your GP can then discuss whether prescription weight management is appropriate for you and what options are available in your area.
How long does it take to see results with weight loss medication?
Most people begin noticing changes within 4–6 weeks, though full effects typically develop over 12–16 weeks as doses are increased gradually. Weight loss continues for several months. Results vary based on dose, diet adherence, and physical activity. Progress tracking helps monitor your individual journey.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.